Lesson 5.4 · Shapes with line symmetry
Hua's Classroom for Shanghai Maths — One Lesson One Exercise (English edition, pages 115–117).
Lesson Alignment
How this Shanghai Maths lesson connects to learning goals, Common Core, and Eureka Math.
Learning Objectives
Students will be able to:
- 01Identify shapes with line symmetry and draw lines of symmetry.
- 02Recall how many lines of symmetry common shapes have.
- 03Complete the other half of a symmetric figure; explore capital letters.
Common Core Standards
| Code | Standard (focus for this lesson) |
|---|---|
| 3.G.A.1 | Understand shared attributes of shapes. |
| 4.G.A.2 | *(preview)* Classify figures; lines of symmetry. |
| 4.G.A.3 | *(preview)* Line symmetry. |
Eureka Math Correspondence
| Shanghai Maths | Focus | Eureka Math |
|---|---|---|
| Symmetry | Lines of symmetry | G4 M4 preview / G3 geometry |
Core Concepts
Recognise reflection symmetry and count lines of symmetry.
Line of Symmetry
A fold line where both halves match exactly.
Squares, Rectangles, Triangles
- Square: $4$ lines of symmetry.
- Rectangle (not square): $2$.
- Equilateral triangle: $3$.
Letters & Folding
Which capital letters are symmetric? Fold a square twice and punch a hole — predict the pattern when unfolded.
Key Terms & Definitions (Reference)
Quick glossary for this lesson.
| Term | Definition |
|---|---|
| Line symmetry | Figure matches across a mirror line. |
| Line of symmetry | The mirror / fold line. |
Key Answers
Quick reference for this lesson’s exercise answers.
1–2. √; √; ✕; √; ✕ — draw lines on the three with symmetry.
3. Square $4$; rectangle $2$; equilateral triangle $3$.
4. MC — C; B; B.
5. Digits — $0$, $1$, $3$, $8$.
6–8. Complete the mirror half (drawings).
7. Letters — A, B, C, D, E, H, I, K, M, O, T, U, V, W, X, Y.
9. Line symmetry; infinitely many ($\infty$) lines.
10. $4$ ways.